Determinação do fator C da EUPS para diferentes culturas no ecótono Cerrado Amazônia

Abstract

The objective of the present work was to determine the Soil Use and Management factor, the C factor of the Universal Soil Loss Equation (USLE), using real data on soil loss under natural rain conditions for soybean and corn crops with brachiaria, in a single plot field experiment carried out for 3 consecutive years in the Cerrado Amazônia ecotone; and the determination of rainfall erosivity (R factor) in the period between the years 2012 to 2015 using the precipitation occurred at the time of cultivation, through a model calibrated for the study region. The experiment of the present work was carried out in the municipality of Sinop, located in the State of Mato Grosso, in the experimental field of the Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Agrosilvipastoril. The soil at the site of the experiment was classified as Dystrophic Red Yellow Latosol, having clayey texture and moderate A horizon and the relief being classified as smooth-wavy (from 3 to 8%). The region's climate according to the Köppen-Geiger classification is Aw (hot tropical climate, with rain in summer and dry winter). The dimensions of the plot were 22 m long and 6 m wide resulting in an area of 132 m2 . The average slope of the plots was 1.5%, which was later corrected to the slope of 9% of the standard plot. Sample collections for the determination of soil losses were carried out after rain events that generated runoff, in the years 2012, 2013, 2014 and 2015. Precipitation varied widely between years, ranging from 2,709 mm in 2013 to 1,522 mm in 2015. The highest annual erosivity value obtained was 17,630 MJ*mm ha-1 *h-1 in 2013 and the lowest annual value was 13,491 MJ*mm ha-1 *h-1 in 2015. Factor C values for soybean were 0.2260; 0.1976 and 0.3009 in the respective planting periods of 2012/2013, 2013/2014 and 2014/2015. The C factor values for corn with brachiaria were 0.1154 and 0.1489 respectively in the years 2013 and 2014. The C factor values for the soybean and corn with brachiaria succession were 0.3414 and 0.3465 in the years 2013 and 2014. The final average values for soybean, for corn with brachiaria and for succession were 0.2415; 0.1321 and 0.3439, respectively.